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GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L13305, doi:10.1029/2005GL023163, 2005

High temperature elastic anisotropy of the perovskite and post-perovskite polymorphs of Al₂O₃

Stephen Stackhouse

Department of Earth Sciences, University College London, London, UK

John P. Brodholt

Department of Earth Sciences, University College London, London, UK

G. David Price

Department of Earth Sciences, University College London, London, UK

Abstract

Finite temperature ab initio molecular dynamics calculations were performed to determine the high temperature elastic and seismic properties of the perovskite and post-perovskite phases of pure end-member Al₂O₃. The post-perovskite phase exhibits very large degrees of shear-wave splitting. The incorporation of a few mole percent of Al₂O₃ into MgSiO₃ is predicted to have little effect on the perovskite to post-perovskite phase transition pressure and seismic properties of the post-perovskite phase; although a small difference in shear-wave splitting may be observable.

Received 6 April 2005; accepted 18 May 2005; published 6 July 2005.

Index Terms: 3620 Mineralogy and Petrology: Mineral and crystal chemistry (1042); 3909 Mineral Physics: Elasticity and anelasticity; 8124 Tectonophysics: Earth's interior: composition and state (1212, 7207, 7208, 8105).

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Citation: Stackhouse, S., J. P. Brodholt, and G. D. Price (2005), High temperature elastic anisotropy of the perovskite and post-perovskite polymorphs of Al₂O₃, Geophys. Res. Lett., 32, L13305, doi:10.1029/2005GL023163.

Copyright 2005 by the American Geophysical Union.